Inertial sensing instruments such as gyroscopes and accelerometers are often mounted on a platform or block. The block is then mounted in an enclosure using elastomeric vibration isolators. For a cube-shaped block, it is desirable to attach the isolators to the corners of the block because it creates favorable dynamic response characteristics and saves space. In the case of corner-mounted vibration isolators, the corners of the block are shaved off to create a flat surface on which to mount the isolators.
Referring to FIGS. 1A, 1B, and 2, a block 14 includes attached micro-electromechanical system devices such as gyroscopes or accelerometers (not shown), beneath protective covers 8 attached to faces 9 of the block 14. Vibration isolators 10 according to the prior art are attached to each corner 11 of the block 14.
A prior art isolator 10 includes an elastomeric damper 18, made of rubber, silicon, or other elastomeric materials known in the art. Example isolators 10 are made by many companies, including Barry Controls and the Lord Corporation. The damper 18 is molded to an outer connector 20 and an inner connector 22, both of which may be made of aluminum, stainless steel, or other materials known in the art. The damper 18 prevents contact between the outer connector 20 and the inner connector 22. The isolator 10 is attached to the block 14 at a corner 11 of the block 14 by screwing external threads 24 of the inner connector 22 into a threaded aperture (not shown) in each corner 11, and a screw 16 attaches the enclosure 12 to the isolator 10 via internal threads 26 in the outer connector 20. One problem with corner-mounted isolators 10 is that the tolerances of the enclosure 12, the block 14, and the isolators 10 are of limited precision such that when the block 14 with attached isolators 10 is inserted into the enclosure 12, there are gaps 17 between the isolators 10 and the enclosure 12. When a block 14 with attached isolators 10 is mounted in an enclosure 12 via screws 16 through the enclosure 12 and isolators 10, the isolators 10 are compressed or stretched by some small amount. This distortion of the isolators 10 causes a shift or misalignment of the block 14 with the enclosure 12, which can be on the order of 0.02 inches on a one inch diameter isolator 10. This distortion alters the vibration isolation characteristics of the isolators 10.